Steam



Sept. 1, 1964 R. M. NEEL 7 3,147,199

RECOVERY OF NICOTINE FROM DILUTE AQUEOUS SOLUTIONS THEREOF BY DISTILLATION AT SUPERATMOSPHERIC PRESSURE Filed Dec. 28, 1961 STEAM AMMONIA F l r k I PRESSURE FRACTIONATING CONDENSER COLUMN HEAT 1 EXCHANGER STEAM COOLER K k r f 20 DEANTE@ REBOILER 36 54- 0 NICO' FINE IN V EN TOR. Faber?! /1 eel United States Patent 3,147,199 RECQVERY 0F NTCGTINE FRUM DILUTE AQUE- QUS SOLUTEGNS THEREOF BY DISTHLLATION AT SUEERATMOSPHERIC PRESSURE Robert Monroe Neel, Winston-Salem, N.C., assignor to R. J. Reynolds Tobacco Company, Winston-Salem, N.C., a corporation of New Jersey Filed Dec. 28, 1961, Ser. No. 162,825 6 Claims. (Cl. 2251) This invention relates to a process for recovering nicotine from dilute aqueous solutions thereof.

As is known, nicotine occurs in varying quantities in the leaf of the tobacco plant from which it can be volatilized using ammonia and steam. This process involves treating tobacco with ammonia in order to disengage the nicotine from the salts in which it is present in the tobacco by replacing it with ammonia. The free nicotine and ammonia are then removed from the tobacco with the aid of steam. The condensate resulting from this procedure comprises nicotine-water solutions in which the content of nicotine, while variable, is generally within the range from about 0.5 to 1.8%. Because of the commercial value of nicotine it is highly desirable that it be recovered from these condensate nicotine-water solutions. The recovery of nicotine from dilute aqueous solutions by simple distillation is complicated by the fact that upon distillation at atmospheric pressure a nicotine-water azeotrope is formed in which the maximum nicotine content is about 2.52 percent. Recovery of such an azeotrope by distillation at atmospheric pressure is not at all practical, the equilibrium vapor and liquid composition being sub stantially the same in the range from about 0 to 2.52 percent.

It is therefore one of the objects of this invention to provide a process whereby nicotine is efiiciently recovered from dilute aqueous solutions by distillation.

The process of the present invention makes possible the recovery of nicotine from dilute aqueous solutions thereof Without the use of solvents or other additives and with minimum waste disposal problems. When the process of the invention is employed to recover nicotine from dilute aqueous solutions containing ammonia such as the condensate solutions resulting from tobacco denicotinizing operations, maximum recovery of the ammonia is also achieved.

The process of the present invention and the advantages attending its use are attributable in great part to the initial distillation of the dilute aqueous nicotine solution at high pressures. It has been found that by distilling dilute aqueous nicotine solutions at pressures above about 65 pounds per square inch absolute that the nicotine content of the azeotrope which is distilled overhead can be increased to a concentration appreciably above 6.9 percent by weight. As is known in the art, aqueous nicotine solutions containing nicotine in amounts more than about 6.9 percent characteristically separate at elevated temperatures into two phases containing about 6.9 percent and about 81 percent nicotine respectively. Therefore, utilizing this discovery and taking advantage of the charac teristic phase separation phenomenon, it is possible by means of distillation to obtain highly concentrated nicotine solutions from dilute aqueous solutions thereof.

The process of the present invention is described in detail in conjunction with the accompanying drawing in which FIGURE 1 is a diagrammatic flow sheet illustrating one presently preferred embodiment of the invention.

Referring to FIGURE 1, a dilute aqueous solution which, for purposes of illustration, comprises the condensate from a tobacco denicotinizing operation, is introduced into multiplate pressure fractionating column 3,147,199 Patented Sept. 1, 1964 through line 12 by means of pump 14. Fractionating column 10 is operated at a pressure of at least about 65 and up to about 300 pounds per square inch absolute and a temperature sufiiciently high to distill the aqueous nicotine solution. Preferably, fractionating column 10 is operated at a pressure of from about 215 to 255 pounds per square inch absolute and in a temperature range from about 190 to 200 C. When fractionating column 10 is operated at the preferred operating conditions the dilute aqueous nicotine solution is fractionated to remove the nicotine and ammonia in an 8 to 10 percent nicotine content overhead. The overhead vapor from fractionating column 10 comprising an 8 to 10 percent nicotinewater azeotrope is taken oif via line 16 and passed to shell and tube heat exchanger 13 where it is condensed.

The heat exchanger 18 serves as a condenser for the overhead vapors from column 10 and as an evaporator for the water in the bottoms from the column 10. The vapors enter the tube side of the heat exchanger through line 16 at the column operating pressure, but the water is allowed to partially flash into the shell side of the heat exchanger through a pressure reducing valve in line 26. Therefore, with the high pressure vapor in the tubes they are kept at a temperature of about 190 C., which is hot enough to convert the water in the underflow into steam for reuse in the denicotinizing operation. A small amount of water is bled off from the shell side of the heat exchanger through line 19 in order to flush out any non-volatiles entering the system.

Water plus traces of nicotine and non-volatile materials comprise the bottoms from the fractionating column 10, portions of which are passed through line 20 to shell and tube reboiler Z2 and through line 26 to heat exchanger 18. Steam at a pressure of about 300 pounds per square inch gauge is introduced via line 24 into reboiler 22 to vaporize a part of the bottoms, with the vapor being passed via line 28 to fractionating column 10 to supply heat thereto.

The condensate from heat exchanger 18 is passed through line 32 to cooler 34. Condensate passes through the tube side and cooling water through the shell side of the cooler. Cooler 34 is preferably maintained at a temperature of about 95 100 C. so as to effect a phase separation of two aqueous nicotine solutions containing approximately 6.9 percent and 81 percent nicotine respectively. This phase separation phenomenon occurs when an aqueous solution containing more than about 6.8 percent nicotine is held at a temperature within the range from about to 180 C. At a temperature of about C. the relative densities of the phases reverse with the high nicotine content phase being the lighter above this temperature. After the desired temperature reduction is accomplished in cooler 34, the nicotine containing solutions together with ammonia vapor flow into decanter 36. The 6.9 percent nicotine phase which separates in decanter 36 is taken off via line 38 and pumped by means of pump 40 as reflux to fractionating column 10. The ammonia and 81 percent aqueous nicotine phase which separates in decanter 36 are passed via lines 42 and 44 through pressure reducing valves to stripping column 46. The stripping column 46 is operated at atmospheric pressure and heated with steam to a temperature of about C. to strip the ammonia as overhead. The overhead is passed via line 48 to condenser 50 to condense water and nicotine from this vapor. The condensate is returned to stripping column as reflux and the ammonia plus any other volatiles are piped off for recycling if desired. The 81 percent nicotine content solution passes as underflow from stripping column 46 via line 52 to receiver 54.

The fact that azeotropes containing nicotine in concentrations appreciably above 6.9 percent by weight can be obtained by distillation at the specified high pressures is clearly shown from the following experimental procedures and data.

The following description and results relate to three experimental runs wherein dilute aqueous nicotine solutions were distilled at a pressure of about 95 pounds persquare inch absolute and a temperature of about 155- 161 C. The charge solution in each instance was either a nicotine-water solution or a condensate resulting from a tobacco denicotinizing operation which contained water, ammonia and nicotine plus traces of other tobacco constituents. All of these runs were made utilizing from 2200 to 2500 milliliters of the charge solution which were introduced into a distillation apparatus and heated until all air and a large part of ammonia was vented from the system and refluxing began. All runs were made with about the same heat input, and total boil-up at the pressure of 95 pounds per square inch absolute was about 14 milliliters per minute measured as overhead condensate. After distilling under total reflux for three to five hours product take-off was initiated at a rate which usually varied from about 0.5 to 0.7 milliliter per minute. This resulted in a reflux to product ratio between 19:1 and 27:1.

Run #1 was made, starting with a 1.04 percent nicotine solution as charge without any ammonia present. A 10.8 percent nicotine content overhead vapor sample was obtained after total reflux and a 7.1 percent nicotine content sample was taken continuously as reboiler nicotine content dropped to 0.31 percent.

Run #2 was made using as a charge an aged condensate resulting from denicotinization of burley tobacco. The charge contained 0.69 percent ammonia and 0.98 percent nicotine. Fractionating results were then very similar to those of run #1 except that the first 50 milliliters of overhead vapor condensate contained 2.8 percent ammonia as well as 7.7 percent nicotine.

In run #3 a fresh condensate resulting from a tobacco denicotinizing operation was used as charge. Results were similar to those of runs #1 and #2. The extraction and titration method of Cundiff, R. H. and Markunas, P. C. described in the Journal of Analytical Chemistry 27, p. 1650-1654 (1955) was used for all nicotine analyses.

The conditions used and analytical results from all three runs are summarized below in Table I.

TABLE I Data at 95 p.s.i.a. Nominal Pressure [Pot and overhead vapor temperatures 155-161 C. an-322 F.) range; condensate IOU-155 C. (212-311 F.) range] Run N o 1 2 3 Charge Used:

Source Synthetic- Aged Denieo- Fresh Denietmizer Conotinizer densate. Condensate.

Nicotine (percent) 0.98 0.84.

NH (percent) O 1.17.

Volume (ml.) 2,500.

Time on Total Reflux 203.

(min. Time on Take Off (min.)r 187. Sample Analyses (percent N ic.) Time from Start of Reflux 90 min 5.9 103-110 ruin. 120-140 min. 0.29 5.3 2274238 rnin 13.6 241-255 min. 329-338 111111 8.8 (Al.l) 355-365 mm 0.07 (A0.0) 373-391 mm... 0. 07 410-422 mm 0.21 7.6'*

B =Bottoms; V=Overhead vapor; R=Reflux or product; A=

Ammonia.

As seen from the above data, distillation of the dilute aqueous nicotine solutions at a pressure of about 95 pounds per square inch absolute resulted in condensates containing more than 6.9 percent nicotine from which highly concentrated nicotine solutions can be obtained by maintaining the condensate at a temperature of about 95 C. for a period of time to effect a phase separation and coalescence.

Those modifications and equivalents which fall within the spirit of the invention and the scope of the appended claims are to be considered part of the invention.

1 claim:

1. A process for recovering nicotine from a dilute aqueous solution thereof which comprises distilling the said aqueous nicotine solution at a pressure of at least about 65 pounds per square inch absolute, condensing the vapor obtained from said distillation to obtain a condensate containing more than 6.9 percent nicotine, maintaining said condensate at a temperature within the range of C. to 180 C. for a period of time to effect separation of two liquid phases at least one of which has a nicotine content above about 6.9% by weight, separating the higher nicotine content phase from the lower nicotine content phase, and recycling the lower nicotine phase for further distillation at a pressure of at least about 65 pounds per square inch absolute.

2. A process for recovering nicotine from a dilute aqueous solution thereof which comprises distilling the said aqueous nicotine solution at a pressure of at least about 65 pounds per square inch absolute, condensing the vapor obtained from said distillation to obtain a condensate containing more than 6.9 percent nicotine, maintaining said condensate at a temperature of about C. for a period of time to effect separation of two liquid phases containing 6.9 percent nicotine and 81 percent nicotine respectively, separating the said 81 percent nicotine phase from the said 6.9 percent nicotine phase, and recycling the said 6.9 percent nicotine phase for further distillation at a pressure of at least about 65 pounds per square inch absolute.

3. A process for recovering nicotine from a dilute aqueous solution thereof which comprises distilling the said aqueous nicotine solution at a pressure of from about 215 to 255 pounds per square inch absolute, condensing the vapor obtained from said distillation to obtain a condensate containing more than 6.9 percent nicotine, maintaining said condensate at a temperature of about 95 C. for a period of time to eflfect separation of two liquid phases containing 6.9 percent nicotine and 81 percent nicotine respectively, separting the said 81 percent nicotine phase from the said 6.9 percent nicotine phase, and recycling the said 6.9 percent nicotine phase for further distillation at a pressure from about 215 to 255 pounds per square inch absolute.

4. A process for recovering nicotine from dilute aqueous ammonia-containing solutions thereof which comprises distilling the said aqueous nicotine solution at a pressure of at least about 65 pounds per square inch absolute, condensing the vapor obtained from said distillation 'to obtain a condensate containing more than 6.9 percent nicotine, maintaining said condensate at a temperature of about 95 C. for a period of time to effect separation of two liquid phases containing 6.9 percent nicotine and 81 percent nicotine respectively, distilling ammonia from said 81 percent nicotine phase, and recycling the said 6.9 percent nicotine phase for further distillation at a pressure of at least about 65 pounds per square inch absolute.

5. A process for recovering nicotine from dilute aqueous ammonia-containing solutions thereof which comprises distilling the said aqueous nicotine solution at a pressure of from about 215 to 255 pounds per square inch absolute, condensing the vapor obtained from said distillation to obtain a condensate containing more than 6.9 percent nicotine, maintaining said condensate at a temperature of about 95 C. for a period of time to effect separation of two liquid phases containing 6.9 percent nicotine and 81 percent nicotine respectively, distilling ammonia from said 81 percent nicotine phase, and recylcing the said 6.9 percent nicotine phase for further distil- 5 lation at a pressure from about 215 to 255 pounds per square inch absolute.

6. A process for recovering nicotine from a dilute aqueous solution thereof which comprises distilling the said aqueous nicotine solution at a pressure of from about 215 to 255 pounds per square inch absolute, condensing the vapor obtained from said distillation to obtain a condensate containing more than 6.9 percent nicotine, maintaining said condensate at a temperature within the range of 75 C. to 180 C. for a period of time to efiect separation of two liquid phases at least one of which has a nicotine content above about 6.9% by Weight, separating the higher nicotine content phase from the lower nicotine content phase, and recycling the lower nicotine phase for References Cited in the file of this patent UNITED STATES PATENTS 1,146,014 Newborne July 13, 1915 1,671,259 Schloesing May 29, 1928 1,684,740 Newborne Sept. 18, 1928 2,478,473 Eskew Aug. 9, 1949 OTHER REFERENCES Bulletin De La Soc. Chem; M.D.E., Tsakalotas, France 10 1909 (pages 397-403 Technique of Organic Chemistry, vol. IV, Distilla tionWeissberger Interscience Publ., Inc., New York, 1951 (page 366 relied upon).

Azeotropic Data, Horsley, June 1952, American Chem.

further distillation at a pressure of from about 215 to 255 15 Washington no (pages 318428 cited).

pounds per square inch absolute. 

1. A PROCESS FOR RECOVERING NICOTINE FROM A DILUTE AQUEOUS SOLUTION THEREOF WHICH COMPRISES DISTILLING THE SAID AQUEOUS NICOTINE SOLUTION AT A PRESSURE OF AT LEAST ABOUT 65 POUNDS PER SQUARE INCH ABSOLUTE, CONDENSING THE VAPOR OBTAINED FROM SAID DISTILLATION TO OBTAIN A CONDENSATE CONTAINING MORE THAN 6.9 PERCENT NICOTINE, MAINTAINING SAID CONDENSATE AT A TEMPERATURE WITHIN THE RANGE OF 75*C. TO 180*C. FOR A PERIOD OF TIME TO EFFECT SEPARATION OF TWO LIQUID PHASES AT LEAST ONE OF WHICH HAS A NICOTINE CONTENT ABOVE ABOUT 6.9% BY WEIGHT, SEPARATING THE HIGHER NICOTINE CONTENT PHASE FROM THE LOWER NICOTINE CONTENT PHASE, AND RECYCLING THE LOWER NICOTINE PHASE FOR FURTHER DISTILLATION AT A PRESSURE OF AT LEAST ABOUT 65 POUNDS PER SQUARE INCH ABSOLUTE. 